The present invention relates to an instrument that can be inserted into the human body, this instrument being provided with at least one channel for fluid and, in particular a gas which is introduced into the inside of the body.
By way of illustration in laparoscopic operations, it is usually necessary to introduce a fluid and, in particular a gas, such as by way of illustration CO2 into the body cavity into which incision was made in order that the cavity does not collapse due to the xe2x80x9cexternal pressurexe2x80x9d.
With increasing duration of the operation, the number of incisions as well as the frequency of changing the instruments requires not only large amounts of insufflation gas, but also high insufflation rates. This is especially the case in HF surgery and laser treatment in which the gas has to remove additionally occurring smoke, etc. In the past, flow rates of a few liters per minute used to suffice, however, for some time increasingly higher flow rates are demanded.
However, even at flow rates in the 5 to 7 l/min range, the patient suffers hyperthermia, i.e. a local drop in temperature distinctly below the body temperature.
If (insufflation) devices having even higher outputs, which in the case of the devices that are available on the market reaches up to 15 l/min, or even insufflation devices having flow-through rates up to 40 l/min are employed, as described in the patent literature, the problem of hyperthermia is even more serious than with conventional devices.
Therefore, it has been suggested to provide a means of heating the fluid in the insufflation device. In particular, with gas insufflation devices there is the problem of heating the gas in the insufflation device, because the gas has little thermal capacity, it cools off again in the supply tube on the way to the patient.
Thus, whenever the gas is heated only in the insufflation device, it is necessary to heat the gas to a higher temperature than is actually desired in order that the gas enters the human body xe2x80x9cjustxe2x80x9d at a temperature that corresponds to the body temperature (37xc2x0 C.). However, this has the drawback that the inertia of the system due to the long tube usually required is large in deviations of the temperature from the desired temperature, i.e. the control constant, is large and therefore the temperature constancy is small due to normal fluctuations, the gas therefore may even be introduced at a too high temperature inside the body.
In another attempt to solve the problem of the patient""s hyperthermia, noteably a, i.a., device sold by Wisap, Sauerlach under the name xe2x80x9cFlow-Thermexe2x80x9d uses an additional heatable tube that connects the actual insufflation device to the instrument to be inserted into the human body.
This solution attempt, too, does not ensure optimum temperature control, because the control constant is large due the length of the tube and the possibly strongly varying surrounding conditions along the tube. Moreover, a heatable tube is less pliant and heavier due to the integrated heating means than a normal tube. Thus, it is not as easy to handle as a normal tube.
The object of the present-invention is to ensure in introduction of at least one fluid and, in particular, at least of a gas into the body, excellent temperature control and, in particular, constancy of temperature of the fluid introduced into the body and, in particular, of the introduced gas.
An invented solution to this object is set forth in claim 1. Further embodiments of the present invention are the subject-matter of the subclaims.
An element of the present invention is that the instrument is provided with a heating means for the fluid. The heating means can heat the fluid and, in particular, the gas alone or in addition to a heating means in the insufflation device as well as, if need be, to a xe2x80x9csupportingxe2x80x9d heating means in the insufflation tube.
Preferred at any rate is if the heating means of the instrument xe2x80x9cassumesxe2x80x9d xe2x80x9ccontrolxe2x80x9d of the control procedure.
Disposal of the heating device in the respectively immediately before the human body, noteably in or near the instrument utilized in the human body ensures optimum temperature control with short control constants can occur in such a manner that the fluid, that is the rinsing fluid respectively preferably the gas having excellent constancy of temperature is introduced into the body cavity.
Another advantage of the invented instrument is that the instrument is heated by the heating means itself as well as by the heated fluid. This prevents the instrument and, in particular, an endoscope optics disposed therein from fogging up. It is especially advantageous if the heating means surround that part of the intrument that accommodates the optical system of the system and, in particular of an endoscope, because this ensures optimum heating not only of the fluid but also of the xe2x80x9csensitivexe2x80x9d parts of the instrument.
Furthermore, a conventional supply tube of any length, in particular, a length that can be varied from application to application can be utilized between the insufflation device and the instrument.
Further embodiments of the present invention are set forth in claims 2 and the following claims.
According to claim 2, the heating means can be integrated into the instrument itself. This design has not only the advantage that the optics located in the instrument are, if need be, heated directly along with the instrument, but also, which is not apparent at first glance, that it improves the balance of the weight of the instrument:
Although one usually tries to design the instruments as lightly as possible, this principle is not adhered to with laparoscopes utilized in conjunction with a CO2 laser. In order to compensate for the weight of the CO2 laser respectively the arm connected to this laser, the instrument has to be designed heavier than usual. This requirement can be easily met by building the heating means into the instrument.
As an alternative, the heating means can be disposed in a separate housing which is provided with a fluid inlet and a fluid outlet which is connected via a short piece of tube to the proximal fluid inlet of the-instrument itself. This design not only prevents undersirable top-heaviness in specific applications, but also permits easy upgrading of already existing instruments in such a manner that they functionally comply with the instrument proposed by the present invention.
The use of an electric heating coil and its special design is described in claims 4 to 7.
In the aforementioned alternative, in which the heating means is disposed outside the body, it is preferable if the heating means is provided in the part of the instrument which remains outside the human body. This permits accommodating the heating means as well as parts of the control unit in the thicker than usually designed proximal part of the instrument without impairing the functiona of the instrument.
Another alternative which is suited particularly for existing instruments is set forth in claim 10:
The heating means is provided in a separate housing which is connected in one piece to the conventionally designed instrument. This alternative permits upgrading existing instruments as well.
Claim 11 sets forth that the heating means is provided with at least one temperature sensor whose output signal is applied to a control means which controls the power delivered to the heating means, thereby permitting not only control of the heating output but also control of the set temperature.
The further embodiment put forth in claim 12 is provided with at least two temperature sensors whose output signals are compared for checking the function of the temperature sensors, thereby permitting relatively precise detection of malfunctions.
It is advantageous if the temperature sensor or sensors are disposed as close as possible to the channel through which the fluid flows.
Independent of the exact design of the temperature sensors, it is advantageous if a temperature sensor which can release a safety circuit is disposed as close as possible to the distal end of the instrument.
Many different evaluation algorithms can be used to control the invented instrument. These strategies can be stored in a program memory and called up upon demand.
In any event, any instrument and, in particular, a trocar as well as an as such known laparoscope for surgical applications can be employed in conjunction with the present invention.